I'm wondering if a 3-wire O2 is a definite cure for cold O2 sensor in headers? Just playing around on the bench it looks to me like the heater alone gets the sensor nowhere near required temp (unless mine is broken), so the heater is sort of just a helper. Is this right?

 

I would say its broken. A properly working O2 sensor with a heater will get very hot, its designed to get the O2 up to proper temperature in much less time than the non-heated one.

 

I went through this with my wide band O2 sensor and only got an outside temp of about 120f and was told that is just radiating heat from the element inside.

So I checked a brand new Bosch regular heated O2 sensor and again about 120f outside but if you can get the laser beam down a slot I got as high as 148f after 2 minutes.

O2 sensor needs about 600f to operate properly, I've never torn one apart to check element temp inside.

 

Yes, a heated O2 NB sensor does work with headers. Yes, it also needs some heat from the exhaust. The heater itself isn't enough to get it up to temperature.

RBob.

 

on mine with headers, I could not get into closed loop without the heated O2. After install it takes only about 2 minutes to go closed. And yes it needs engine heat to get that hot. I found my headers were just under threshold to go closed without the extra heat.

 

if you wrap your headers that should help also, right or wrong,

 

Yes wrapping them helps but if you ever get them wet it helps them rust/rot faster too!

Best thing I have experianced was ceramic coated Headman Headers. They keep underhood temps down and keep heat inside header to O2 sensor. I actually ran a non heated NB and it was almost always in closed loop like when NB was when closer to exhaust manifold as stock.

Benifit was they looked like new after a years use and off road abuse.

 

I have Dough Thorley headers. Not sure what coating, but I've had them for 15+ years and they are still shiny. Sort of discolored, but that's it.

 

Ceramic headers can be polished to restore the finish...

 

Actually the O2 sensor is usually put in the collector after the headers so is quite a ways away from the heat source. If it was in the header then there should be no problem. Mine is in the collector about 8 inches beyond the header/collector connection and I had a problem even with ceramic coated headers. Heated O2 solved it and was an easy fix.

 

My Edelbrock headers didn't allow the O2 sensor go into closed loop. I run my car at around 180 degrees and I live in a cold-ish climate compared to most of you guys (I can drive on the highway without the fan turning on and it will stay at 180). I installed a NGK heated 3 wire O2 sensor (from TPIparts.net) and it always goes into closed loop now and it goes into closed loop after just over a minute.